The objectives are to develop general protocols for the synthesis of three different classes of naturally occurring compounds, Eremantholide A, Saudin, and Ginkgolide A, each of which possesses interesting biological activity and which constitute a lead in a different therapeutic area, namely cancer, diabetes, and cardiovascular disease, asthma and stroke, respectively. The syntheses have been planned with the idea that simpler analog structures will become available during our studies to assist in the development of structure activity relationships in these unique classes of compounds. Our studies will explore new strategies and new applications and methods for creation of contiguous quaternary centers, closure of medium rings, and the construction of hetero propellane systems. The problems posed by these densely functionalized cage and bridged ring structures present considerable challenges for contemporary synthetic organic chemistry.